Answers are grounded in this paper and cite their sources.
SUMMARY: The sand from the filter‐beds of a city water supply was found to contain anaerobic bacilli and it is probable that these organisms are added to the water as it passes through, because anaerobes are present in the treated water. Emphasis is laid on the value of the anaerobe test on treated waters in assessing filter efficiency, and the significance of bacterial aftergrowth is pointed out.
No takes yet. Share an insight, caveat, or question.
A. T. Willis (1957) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: